A common machine tool arrangement employed in the mass production of various articles wherein drilling, boring, reaming, grinding, and similar operations involve a rotating tool comprises a tool holding adapter removably attachable to a power driven spindle.
Heretofore, latch mechanisms for releasably securing the tool holding adapter and spindle in operative engagement with each other have employed attachments or spindle adapters that fit over the tool holding end of the spindle and are accessible from that end to enable changing of the tool holding adapter. The concept of such spindle adapters, known generally as over-spindle adapters, has long been approved, especially with multiple spindle machines, because it is usually cumbersome and time consuming to reach into a fairly closely spaced assembly of such spindles to unscrew set screws or operate other mechanisms as required for releasing and replacing the tool holding adapter. By virtue of the over-spindle type of adapter, a tool change can be readily made by accessing a releasable attachment for the adapter at the exposed end of the spindle.
Although the desirability of such over-spindle adapters has long been recognized, the spindle adapters available heretofore leave much to be desired. In particular, a common type of over-spindle adapter employs an axially slidable cam sleeve around the tool holding end of the spindle and maintained in a retracted tool holding position by spring means. The sleeve is provided with an annular cam that holds an annular arrangement of balls within an annular retaining groove in the tool holding adapter, such that the latter cannot be removed from the spindle. Upon axial movement of the sleeve from the retracted position, the cam releases the balls from the retaining groove to enable removal of the tool holding adapter from the spindle.
Such spindle adapters are not only complicated to use and expensive to manufacture, but are also subject to jamming when small chips or fines from prolonged grinding or drilling operations enter the latch mechanism and prevent release of the balls, whereupon the tool holding adapter often must be pried or pounded off the spindle. In consequence an advertised five second tool change might require half an hour or more.
Important objects of the present invention are to provide an improved over-spindle adapter of comparatively simple and economical construction for releasably securing a tool holding adapter to a power driven standard automotive shank spindle; wherein the tool holding adapter can be quickly attached in an operative position to the spindle, or quickly released, usually by finger manipulation; wherein the latch mechanism of the spindle adapter for attaching and releasing the tool holding adapter relative to the spindle is at all times shielded from particles of dirt, grindings, chips and fines resulting from machining operations; wherein a positive rotary drive mechanism between the spindle and tool holding adapter is completely independent of the latch mechanism; and wherein the present invention is especially suitable for use with multiple spindle machines or in small diameter machining applications.
Another object of the invention is to provide such a spindle adapter that is readily coupled with a standard automotive shank spindle without requiring any modification of the spindle. The spindle adapter comprises a sleeve extending around and keyed to the tool holding end of the spindle by means of a special set screw that replaces the set screw conventionally used to secure the tool holding adapter within the spindle. A retention and rejection collar rotatable coaxially but not movable axially on the sleeve is provided with an internally threaded portion in screw threaded engagement with external threads of an annular nut that also has internal threads screwed on external threads of the tool holding adapter to a desired position of adjustment, whereby upon rotation of the collar in one direction or the other, the adapter is moved axially into or out of an operative position within the conventional coaxial endwise opening recess in the spindle.
A conventional spline engagement between the spindle and tool holding adapter at the operative position provides a positive drive (independent of the latch mechanism) for rotating the adapter upon rotation of the spindle. Also the threaded connection between the collar and the nut on the tool holding adapter is arranged so that rotation of the collar in the direction for moving the adapter to the operative position is opposite the rotational direction of the spindle during its power operation.
The above mentioned annular nut screwed on the tool holding adapter replaces the nut that is conventionally used and adjusted axially on the adapter to determine the axial position of the tool held by the adapter. The annular nut provided by my invention also abuts the spindle end tightly in annular sealing engagement around the endwise opening into the spindle recess when at said operative position. In accordance with the present invention, the annular nut is conventionally adjusted axially along the adaptor and then secured at its adjusted position by a set screw that screws radially into the annular nut and tightly against the adapter. At the tightened position of the set screw, its radially outer end is recessed below the external threads of the nut so as not to interfere with the aforesaid threaded engagement between the internally threaded collar and externally threaded nut. By reason of the latter engagement, the nut, secured at its adjusted position on the tool holding adapter, is drawn tightly into said annular sealing engagement with the spindle to prevent entry of grinding fines into the endwise opening spindle recess simultaneously with locating the tool holding adapter at its operative position.
Other and more specific objects are to provide the threaded connection between the collar and tool holding adapter with an acme type thread dimensioned to move the adapter from its operative position within the spindle to a position out of engagement with the collar upon approximately a single full turn of the collar; and to provide effective means for retaining the collar against axial movement along the sleeve while enabling freedom of rotation comprising a resiliently and radially expandable and contractible ring, such as a C-type ring for example, having radially inner and outer peripheral portions confined respectively within confronting coaxial annular grooves in the outer periphery of the sleeve and an overlying inner cylindrical surface of the collar; wherein the load bearing sides of the radially resilient ring are plane surfaces normal to the axis of the spindle and closely confined between parallel sidewalls of the confronting annular grooves.
Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.